Device for injecting fuel into internal combustion engines



Aug. 20, 1935. K. .1. E. HEssELMAN DEVICE EoR INJECTING FUEL INT0INTERNAL coMEUsTloN ENGINES Filed Aug. 26, 1930 lig. 2.

Inventor: Knut Jj. E.l-lesselmann1 M H'Ls Attorney.

Patented Aug. 20, 1935 PATENT olivier: 1

nEvIcE'Fon rNJEcrlNG FUEL rN'ro INTER.-

' NAL ooMUs'rIoN ENGINES v Knut Jonas Elias Hesselman, SaltsjoStorangen,

' Sweden Applicaumnngust 26, 1930, serial No. 417,932 I. Y In SwedenSeptember'9, 1929 s y .A

' scams. (ci. 12s-139) This invention relates to devices for injectingfuel into internal combustion engines of the kind which consist ofpumping means, such as aA fuel pump, and one or more injection nozzleshaving, however, no special fuel valve but only one or more pressurevalves between the piston of the fuel pump land the injection, nozzle ornozzles. In such devices it is known to interrupt A the lfuel injectionby means of a special relief w valve which is opened during thecompression stroke of the pump piston and thus places the compressionside of the pump in communication either with the suction pipe of thepump or with a special pipe which leads the oil flowing through therelief valve back to the fuel container. 0n the opening of the reliefvalve during the compression stroke of the pump'piston, the pressure intheI pump space and the pressure pipe drops quickly to about atmosphericpressure. The

closing movement of the pressure valve does not take placeinstantaneously upon this drop, hown ever light the valve may be andhowever powerful its spring loading. As a result there is an opportunityfor thehigh pressure which is set up in the, motor cylinder during theinjectionl to force a part of the -oil back past the pressure valvebefore the latter has had time to close'. This in turn results in hotgases flowing through the fine holes in the injection nozzle into the*sup- 30 ply passage in the neighborhood of these holesand-producingxcoking or carbonization of the` oil in the holes and inthe passage behind them. Such coking has a harmful influence on theinjection process and on the atomization of the 35` oil.

'I'he object of the invention is to prevent the oil from iiowing. backinthisway. With this object in view, the relief valve, according to thepresent invention, opens into a' space provided 40 with arspring-loadedoutlet valve, the springloading of which is such that this outlet valvel opens at a pressure which approximately correspends to or exceeds thepressure present in the .combustion space of the mtorat the end of the45 injection, that-1s at the instant when the reliefv vvalve is opened.This valve arrangement makes y it impossible for the pressure in' thepump space to dop at the end ofthe injection period below p the pressurein the combustion space of the mo- 50. tor. Flowing back ofthe oil asdescribed above is therefore prevented, as also is any coking inthe`holes ofthe nozzles or in the passage bef hind them. .After thepressure valve has once returned to its closed position, .it can, ofcourse,

' 65 peassumed that-a win hom tight and 1t is there- `the movable valvemember fore possible subsequently to allow the pressure in the pumpspace to drop without risk.

In'order that the," vention may be clearLv understood and readilycarried intoeifect, two de-4 vices constructed in accordance therewithnow be described by way of 4example with reference to the accompanyingdrawing in which Figures 1r an'd 2 show longitudinal sections throughthe two devices. The device shownin Figure l is applicable to a lowpressure motor in which lo l the end ofthe injection takes place at thesame crank angle at all loads, while in Figure 2 a. device is shown fora motor with compression ignition in which 'the beginning of theinjection l remains constant but ,the end of the injection 15 may bevaried by opening the relief valve earlier or later in any Ysuitablemanner.

f Referring first to Figure 1, the pump casing of a fuel pump or supplymeans is shown at I andthe pistonat 2. The piston 2 is driven by a cam 320 fixed-on ashaft 4. rlhis shaft can, for instance,` be the controlshaft of an explosion or prolonged combustiomengine. As shown in thedrawingthe pump is` provided with a suction valve 5, which y controlsthe communication between the pump f5 space or compression chamber andthe suction passage l, and also with a pressure or check valve 8 whichisarranged at the'end of a pressure supply passage 9 immediately in frontof an injection nozzle III. The latter projectainto the combustion spaceof a motor which-is not shown. A Arelief valve` I I is provided on abore in line with the piston 2 and is opened by the piston 2 during thestroke. of the latter for the purpose of interrupting the fuel supply.The relief valve II controis the communication between the pump space ory compression chamber 6 and a chamber I2k which is separated from thesuction passage I by al spring-loaded valve I3. The spring for biasingtowards its seat is located between the valve member and an ad. justableplug screwed into a threaded hole of the pump casing. The spring-loadingor biasing of this valve I3 is made such that the pressure re- K quiredto open the valve is ofthe order of the pressure in the combustion spaceof the motor at -thne end of the fuel injection, that is on the openingof the relief valve II. The valve I3 thus ensures that at theinterruption of the injection the pressurein the pump space l shall notdrop below the pressure in the cylinder. The closing of the pressurevalvef 'at the end of the injection period is effected bythe pressure inthe combustion space and the spring for the valve. 'I'he pressure withwhich the spring forces the valve towards its combustion space at'thetime when valve 8 closes.

The slower closingv of the pressure valve 8 has the advantage also thatit minimizes undesirable` osclwlations o f Y'the fuel in conduit 9. Therisk mentioned above of coking or carbonizing in the outlet holes or inthe passage lof the nozzle I0 is consequently removed, since on accountof the said pressure ratio no oil will iiow back past thepressure valve(8. The pressure required to open the valve I3 is, however, lower thanthat required to open the pressure valve 8, so that during the furthermovementof the piston 2, after this has opened the relief valve I I, oilcan flow back from the chamber I2 to the suction passage 1.

In order that the pressure valve may be securely held inits closedposition, the relief valve i may beI arranged in such a way that on thefurther movement of the pump piston the pressure in the pump space 6 orchamber I2 drops. This is effected, in the construction shown in Figure1, by providing the relief valve I I with a passage I4 which opens abovethe guide I5 of the valve rod when the relief valve moves furtheroutward. This arrangement has the advantage that any air which may bepresent in the pump space on the `starting of the motor is given anopportunity of escaping freely through the relief valve.v

In the construction shown in Figure 2, I as before indicates the pump orfuel supply casing, 2 the pump piston, 3 the driving cam, 4 the camshaft, 5 .the suction valve, 6 the pump space or compression chamber and1 the suction pipe. In this construction the pressure valve 8 isarranged ina special valve casing 23 immediately before an injectionnozzle I0, the valve casing being mount- Ied in the cover of a motorcylinder and being placed by a pipe l24 in communicationwith thepressure'passage 9 in thepump casing I. The cam 3 in this case actuatesthe piston 2 througlr biasingmeans, such as a spring-loaded intermediatemember 20. The relief valve II is not actuated by the piston but by alever arm 2| actuated by the intermediate member 20 and carried on aneccentric 22, so,that it' can be set to open the relief valve earlier orlater during the compression stroke of the piston 2. The relief valvecontrols the communication between the pump space or ...compressionchamber 6 and'a chamber I2, from which a passag'e 25 and a pipe 26 leadtothe suction pipe 1. The spring-loaded valve I3 is placed in thepassage 25. The spring-loadingj'of this valve is determined in"the'sameway as is described above with reference to thevalve I3ishown Inthisconstruction also a pressure-reducing and air escape passage I4 isprovided in the spindle of the relief valve II, and places the chamberI2 in communication with a by-pass passage 21,

leading to the passage 25, after the valve II has opened to a givenextent. The invention is not limited to the constructions described butmay be applied to other constructions. Fo'r example the air escapepassage I4A not necessary. In the absence of this, a, pressure ispreferably maintained inv the pump space which, during the whole timethat'there is pressure in the cylinder space; is higher than thatpressure. The height of the pressure in the pump space is determined bythe spring-loading of the valve I3, and the time during which thepressure must be maintained is adjusted by the cam 3 of suitabledimensions. Again when provision is made for reduction of pressure orescape of air, the passage I4 may be replaced by any suitable passage oropening controlled by the relief valve and uncovered or opened after thelatter has `moved off its seat through a predetermined disltance.

I have described the principle of operation of my invention, togetherwith the apparatus which I now consider to represent the best embodimentthereof; but I desire to have it understood that the apparatus shown isonly illustrative and that the invention may be carried out by othermeans.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. In combination with an engine having 4a combustion cylinder, a devicefor injection of fuel into the cylinder, said device including a fuelpump comprisingv a compression space and a piston, at least one fuelinjecting nozzle in said cylinder, a conduit for connecting said nozzlewith the compression space, a pressure valve be'- -tween the pump andthenozzle, a relief valve opening into the compression space, a chamberdefined by the pump casing; said relief valve opening into said chamber,a spring-loaded outlet valve in said chamber, said outlet valve being soloaded by the spring, that the pressure necessary to open it is of theorder of the pressure in backflow of gases from the combustion spaceinto the compression space during the opening of the relief valve andbefore the pressurevalve is seated.

2. In combination with an engine having a combustion cylinder, a devicefor injection of fuel into the cylinder, said device including a fuelpump, a piston in said pump, at least one fuel injecting nozzle in saidcylinder, a pipe connecting said nozzle with the compression space ofsaid pump, apressure valve between the pump and the nozzle, a reliefvalve in said pump, a spacefin said pump, said relief valve opening intosaid space, a spring-loaded outlet valve in said space, said outletvalve being so loaded by the spring, that the pressure necessary to openit at least corresponds to the pressure in the combustion space of thecylinder at moment at which the relief valve is opened, a bypass forsaid outlet valve, said bypass leading from: said pump space and beingopened after said relief valve has moved oi itsseat through apredetermined distance.

3. In combination with an engine having a combustion cylinder, means forinjecting fuel into the cylinder comprising a compression chamber, pumpmeans for supplying fuel to the chamber, a conduit between the chamberand the cylinder, a check valve means including a biasing spring in theconduit and means including said check valve for interrupting the fuelinjection to the cylinderA comprising a valve means, and means forbiasing the valve means against its seat with a pressure of the order ofthe pressure existing in the combustion space of the cylinder at themoment when the check valve'means is closed to prevent back flow of fuelfrom the cylinder into the conduit.

the combustion space of the cylinder to prevent y 4. lIn combinationwith an engine havingv 9x75 combustion cylinder, means for injectingfuel into the cylinder, a fuel pumping means having a compressionchamber, a conduit between the compression chamber and the fuelinjecting means, a pressure valve means in the conduit, another chamber,a relief valve means between the compression chamber of the pumpingmeans and the other chamber actuated by the pumping means, an outletvalve in the other chamber, and means for biasing the outlet valveagainst its seat with a pressure of the order of the pressure existinginthe combustion space of the cylinder at the moment when the reliefvalve isl opened.

`5. In combination with an engine having a combustion cylinder, a nozzlefor injecting fuel into the cylinder, a fuel pump comprising acompression chamber and a piston, a conduit between the compressionchamber and the nozzle, a pressure valve in theoconduit, means forsupplying fuel to the compression chamberfanother chamvber adjacent thecompression chamber, a relief valve between the two chambers actuated bythe piston, an outlet valve for the other chamber, and means biasing theoutlet valve against its seat with a'pressure of the order of thepressure in the combustion space of the cylinder and adapted to permitopening of the valve when the relief valve is opened, the pressure ofthev biasing means being lower than the pressure for forcing thevpressure valve against its seat.

KNUT- JONAS ELIAS HESSELMAN.

